# Studies of feeding behavior, development, and food limitation in first feeding nauplii of the copepod {\it Acartia tonsa\/} (Copepoda: Calanoida)

#### Abstract

Food limitation of production by naupliar stages of marine copepods is poorly understood. This dissertation focuses on aspects of food requirements and the question of food limitation of first feeding nauplii of the copepod Acartia tonsa.^ Laboratory studies were conducted to investigate naupliar feeding behavior. Small flagellates and dinoflagellates less than about 15 $\mu$m in size were found to be the best food source, while diatoms and chlorophytes were a poor food source. High concentrations of the dinoflagellate Heterocapsa pygmaea (540 $\mu$gC/1, 80 $\mu$gN/1) were required for maximum development rates. High ingestion rates (mean 1110% body C/day) were found, but no pattern between total ingestion in terms of C or N and cell size or phytoplankton type was observed. Respiration rates of feeding nauplii were 4 times greater than starved animals in filtered seawater. High naupliar metabolic rates when feeding on food of poor nutritional quality may accelerate starvation.^ Morphometric analysis was used to assess the condition of individual nauplii (N3) of the copepod Acartia tonsa that were either reared in the laboratory or collected from a 13 m$\sp3$ mesocosm. Nauplii grown on a mixed phytoplankton diet were larger than those grown on Dunaliella tertiolecta, a poor food source. Measurements of shape were not significantly different. A laboratory derived discriminant function based on morphometric measurements was used to assess the condition of nauplii collected from the mesocosm. The discriminant function correctly classified nauplii in poor condition during periods of high mortality and slow development, and was also successful at identifying nauplii in good condition when mortality was low and nauplii were developing at near maximal rates.^ A comparison of the effects of food limitation between Acartia tonsa adult females and first feeding nauplii was conducted during the summer and fall of 1988 in lower Narragansett Bay. Measurements of growth and egg production of adult females in ambient bay water and algae enriched bay water indicated that the animals were continuously food limited. Morphometric measurements of nauplii collected from the field and development rates of nauplii in laboratory experiments indicated that the nauplii were also food limited. ^

#### Subject Area

Biology, Oceanography

#### Recommended Citation

Robert George Campbell, "Studies of feeding behavior, development, and food limitation in first feeding nauplii of the copepod {\it Acartia tonsa\/} (Copepoda: Calanoida)" (1993). Dissertations and Master's Theses (Campus Access). Paper AAI9332426.
http://digitalcommons.uri.edu/dissertations/AAI9332426

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